A211508 - OEIS

A211508

Number of ordered triples (w,x,y) with all terms in {1,...,n} and w^2=n-x*y.

0, 0, 1, 2, 2, 4, 4, 6, 5, 6, 8, 8, 8, 12, 8, 10, 12, 12, 11, 16, 12, 16, 16, 12, 16, 20, 14, 16, 22, 20, 16, 24, 17, 22, 24, 16, 22, 30, 16, 24, 30, 26, 20, 28, 26, 28, 32, 18, 26, 38, 21, 30, 36, 28, 28, 34, 30, 36, 34, 26, 34, 46, 20, 28, 46, 36, 32, 40, 30, 42, 40

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,4

COMMENTS

For a guide to related sequences, see A211422.

LINKS

Table of n, a(n) for n=0..70.

MATHEMATICA

t[n_] := t[n] = Flatten[Table[w^2 + x*y - n, {w, 1, n}, {x, 1, n}, {y, 1, n}]]

c[n_] := Count[t[n], 0]

t = Table[c[n], {n, 0, 80}] (* A211508 *)

CROSSREFS